It’s also common for parasites to cause one of their host-species to act in a way that makes infected individuals much more likely to get eaten by a second host species. Sometimes this works so well that the parasite becomes dependent on the loop. Other times it is helpful but not mandatory.
Example of transmission improving behavioral change:
cordyceps causing infected ants to climb to a tall place, where wind will be more likely to spread the spores
parasites themselves crawling up onto plants where grazers are likely to unintentionally consume them
Examples of multi-host parasite changes:
parasites causing insect hosts to move to a place where predators will likely eat them (general pattern seen with insects and birds, and with Toxoplasma gondii causing mice to have less fear and be more likely to get eaten by cats), or causing the hosts to compromise their evolved camouflage (e.g. by growing growths w bright tasty colors)
parasites causing insect hosts to move to places where grazers will unintentionally eat them. different from the prey-to-predator path
I think this is fascinating and we are likely to see some interesting evolutionary dynamics emerge. Definitely something to keep an eye on.
It’s also common for parasites to cause one of their host-species to act in a way that makes infected individuals much more likely to get eaten by a second host species. Sometimes this works so well that the parasite becomes dependent on the loop. Other times it is helpful but not mandatory.
Example of transmission improving behavioral change:
cordyceps causing infected ants to climb to a tall place, where wind will be more likely to spread the spores
parasites themselves crawling up onto plants where grazers are likely to unintentionally consume them
Examples of multi-host parasite changes:
parasites causing insect hosts to move to a place where predators will likely eat them (general pattern seen with insects and birds, and with Toxoplasma gondii causing mice to have less fear and be more likely to get eaten by cats), or causing the hosts to compromise their evolved camouflage (e.g. by growing growths w bright tasty colors)
parasites causing insect hosts to move to places where grazers will unintentionally eat them. different from the prey-to-predator path
I think this is fascinating and we are likely to see some interesting evolutionary dynamics emerge. Definitely something to keep an eye on.